Indicative sensor for stock control

ABSTRACT

It&#39;s a device which purpose is to monitor the storage and indicate that a frozen product has been subjected to a thermal variation, with temperature rise, causing the fusion and liquefaction of a fluid (H) contained in said sensor. Said sensor comprises a hollow, cylindrical tube ( 2 ) with an open end ( 3 ), featuring a releasable cap ( 17 ) and a closed end ( 4 ), with a slidable piston ( 5 ) inside the tube ( 2 ). A compartment (C 1 ), inside the tube ( 2 ), placed between the piston ( 5 ) and the end ( 4 ), is fulfilled with a compressed fluid ( 0 )/spring (M), and a compartment (C 2 ) placed between the piston ( 5 ) and the end ( 3 ), is fulfilled with said fluid (H), frozen, in the solid state. Upon the thawing of the product, the fluid (H) also taws, escaping the compartment (C 2 ) and allowing the movement of the piston ( 5 ), pushed by the fluid ( 0 ). Said movement of the piston ( 5 ) is irreversible and constitutes the sensor&#39;s visual indication revealing that the product has been thaw.

The indicative sensor for stock control is a device which main purposeis to indicate that a frozen food, either processed or not, has beensubjected to a thermal variation which caused the fusion of its watercontent initially present in the solid form and later liquefied. A food,either processed or not, once thaw must not be frozen a second time,because such procedure will lower it's quality, under any point of view,such as characteristic texture, flavor and nutritional value. Saidindication by the indicative sensor for stock control of the change ofstate of the water contained in the food is a valuable information forall those involved in the refrigeration chain of said food, from themanufacturer to the distributor, the retail salesman up to the finalconsumer, so that a correct evaluation may be conducted establishingwhether there was or not a breakdown or problem in the wholecommercialization and storage process as far as the refrigeration chainis concerned.

STATE OF THE ART

The creation of devices of several shapes, comprising various substancesand based on several material properties, have been proposed to indicatethe freezing and thawing of pharmaceutical products, beverages, foodproducts and substances which are sensitive to said changes. The numberof existing patents related to the issue testifies the importance ofsaid devices as valuable aids on insuring the correct maintenance ofstorage temperature along the various commercialization steps.

Among said patents we may mention the ones that follow, which disclosedevices to indicate wh ther a given product was submitted to freezing:

U.S. Pat. No. 4,457,253 (Manske)—discloses a capillary device containingsubstances, one of them colorful, of different freezing points inside itseparated from each other by immiscible liquids surrounding a porousrubber plug, colorless or white. The contact between the colorfulsubstance and the porous rubber only occurs after the freezing, when thecolorful substance pigment dyes the rubber indicating the storage of themonitored product in low temperatures.

U.S. Pat. No. 4,846,095 (Emslander)—discloses a device to detectcritical temperature comprising a porous membrane containing twoliquids, being said membrane only wetted if said critical temperature isreached.

U.S. Pat. No. 4,132,186 (Manske)—describes a freezing indicatorcomprising 2 chambers, one containing an aqueous substance that expandsupon freezing; said expansion increases the pressure over the liquidinside the other chamber which causes its passage through a capillaryuntil it reaches the indicator compartment.

U.S. Pat. No. 5,120,137 (Ou-Yang)—describes a device in which aindicator substance is liquefied whenever a certain temperature iseither reached or passed, said substance making contact with a absorbingtape in order to visually register temperature versus time.

Conversely, there are the devices which indicate whether or not acertain frozen product was submitted to thawing, such as the one frompatent U.S. Pat. No. 4,145,918 (Couch et al.) which discloses a thawingindicator in which a water containing flask is ruptured upon freezing byexpansion of the liquid. Said flask is placed inside a transparentcasing over a paper indicator with ink, and the pigment of said ink isdissolved by the thaw water and reveals the change registered by meansof the dying of said paper indicator.

Another device that indicates the thawing of a frozen product isdisclosed on patent WO 99/24799 (Massi) which presented a sensorcomposed of several stacked discs coated with suitable substances thatwork, for example, as facilitators of water permeation or water solubledyes recipient, which associated to different permeation paths stampedon other disc allow the conduction of the water until it reaches thevisible point of the sensor and detector, thus indicating and signalingthe thawing that has occurred.

The thawing indicator devices above feature some inconveniences.

The device of patent U.S. Pat. No. 4,145,918 requires a glass flaskfulfilled with water and a protective capsule that comprises adye-impregnated filter paper. Said constructive disposition does notensure that the liquid contained in the device overflows the protectivecasing upon taw, which may damage the monitored product. Furthermore,the device, being positioned only on the surface of the frozen product,will only indicate the superficial thawing of the product, whereas theinterior of the product remains frozen. Another disadvantage of saiddevice is the fact that the construction of the glass flask is madedifficult by it's particular shape.

Patent WO 99/24799, although bolstering the advantage of the device'slow cost, of not specify either qualitatively or quantitatively thecomponents of the micro-capsules mentioned in the text, lacking saidinformation; furthermore, it features the disadvantage of monitoringonly the superficial thawing of the frozen product. Another disadvantagelies in the fact that an ambient with high concentration of moisturewill make said device produce false indications of thawing due to it'sworking principle which relies on water absorption.

Patent U.S. Pat. No. 5,120,137 features the disadvantage of presenting aband that enables de device's activation, plus the fact that it'sliquefying substance having a toxic nature, which prevents the device tobe placed in intimate contact with food, for example, allowing only asuperficial monitoring of temperature and time. The device's cost isalso considerably high in view of the constructive material involved.

OBJECTS OF THE INVENTION

In view of the above indicated problems, it is an object of the presentinvention to provide a device that allows the monitoring of a product'sthawing, not only superficially, but in an effective manner, of lowcost, and of easy construction and use.

DESCRIPTION OF THE INVENTION

The present invention will be explained based on the figures listedbelow, in which:

FIGS. 1A and 1B are schematic representations of two situations of theindicative sensor for stock control, in it's simplest configuration;

FIG. 2 is a second schematic representation of the present sensor,illustrating its operation;

FIGS. 3A to 3D exhibit some forms of use of the indicative sensor of thepresent invention in contact with food,

FIGS. 4A and 4B show in detail the operation of a constructive variantallowing a better view of the indication of the present invention'ssensor;

FIGS. 5A to 5K show some variants of the possible formats and finishingthat may be used in the present invention;

FIGS. 6L to 6S and 7T to 7W show yet further variants of the possibleconstructive forms of use of the present invention.

FIG. 8 is a third schematic representation of the sensor of the presentinvention.

FIG. 9 is a fourth schematic representation of the sensor of the presentinvention.

The indicative sensor for stock control of the present invention hasapplications, mainly, in the area of frozen food. As seen on FIG. 1A,said sensor 1 comprises, basically, one hollow, cylindrical tube 2,preferably made of a rigid, transparent, opaque or translucent material,with a first end 3 open and a second end 4 closed, with a sliding piston5 inside the tube 2. A compartment C1, inside the tube 2, comprisedbetween the piston 5 and the end 4, is fulfilled with a compressed fluidO, preferably gaseous, such as air, or nitrogen, for example; instead ofthe fluid O the compartment C1 may contain a spring M, compressed, withan end of said spring leaning on the end 4 and the other end of saidspring touching the sliding piston 5 as illustrated on FIG. 8.Optionally, the end 4 features a passing hole 25 to allow the admittanceof air into the compartment C1 upon the movement of sliding piston 5.

Whereas a compartment C2 comprised between the piston 5 and the end 3 isfulfilled with a fluid H, frozen to the solid state, preferably having,however, a liquid constitution at a certain temperature above themonitoring point; the same fluid H must preferably be non-toxic, beingpossibly of a similar nature to that of the food in which the indicativesensor of the present invention will be used. The end 3 features areleasable cap 17, and there is optionally a engraving 6 made on tube 2,and this engraving coincides with the position where the piston 5 is,with the fluid H perfectly frozen.

The indicative sensor for stock control features a very low probabilityof failure, upon monitoring frozen food, once the device's operation isbased on principles already very well proven of Physics and Chemistry.One of said principles is the expansion of the liquid fluids duringfreezing, reflecting, for example in the case of pure water, an increaseof about 10% of it's initial volume. The water expansion force is sogreat, that in the Ancient Age said freezing force was used to displaceboulders in the civil engineering works of the era. Thus, the acting ofthe indicative sensor at hand occurs in the following manner: beforesensor 1 is submitted to a temperature that allows the freezing of fluidH, this is in a liquid state, and the end 3 has its cap 17 placed on, asseen on FIG. 1A; when the sensor 1 is immersed in an ambient whichfosters the freezing of fluid H, the later becomes solid, frozen, andhas its volume expanded, causing the expulsion of cap 17 which thusleaved the end 3 open, free; as the fluid O, gaseous, or alternativelythe spring M, are compressed inside compartment C1, it is under pressureand exerts a spring effect, trying to push the piston 5 towards the end3. However, the fluid H, frozen, contained inside compartment C2, beingin its solid state does not allow the piston 5 to move from its place,regardless of the pressure exerted by fluid O/spring M. This situationremains unaltered for as long as the fluid H remains frozen, that is, aslong as the sensor 1 is immersed in an ambient which temperature iseither equal or lower than the freezing point of said fluid H, as shownon FIG. 1B; but if at any moment the temperature increases to a valueabove the freezing point of said fluid H, thus causing a taw, the fluidH will revert totally or partially to the liquid state and will spillout of said tube 2, through the open end 3. That will allow the piston 5to move inside tube 2, pushed by fluid O/spring M; said movement may beviewed, because piston 5 has left the position corresponding to theengraving 6 as shown on FIG. 2, indicating the occurrence of atemperature rise in the ambient in which sensor 1 was immersed, with theconsequent taw.

Even if said taw occurs only for a brief moment and is followed by a newlowering of the temperature up to a point of re-freezing, as the fluid Hhas escaped to the outside of tube 2 the compartment C2 became empty,and thus there is no element left to prevent the movement of piston 5 ormake it go back to its previous position, on the engraving 6. As theindicative sensor of the present invention must be in physical contactwith the frozen food to be monitored, there is an inerasable register ofwhether there has or has not been thawing of said food.

On FIGS. 3A to 3D are shown some forms of use of the indicative sensorin contact with the frozen food, observing that the cap 17 has alreadybeen expelled from the sensors, leaving its ends 3 free; the packing ofsensor 1 can be, for example, in the outer package, outside of the food,as illustrated on 3A; inserted vertically in the food, as shown in 3B;at least two different sensors 1, placed on a single food, insertedhorizontally, as shown in 3C, so that it is possible to monitordifferent areas of the same food, independently; the sensor 1 isdirectly integrated to a packaging of the “blister” kind wrapped aroundthe food, as shown on FIG. 3D so that said tube 2 configures anintegrated part of the packaging, from which it cannot be dissociated.

In case of thawing, or even extreme mechanical shock, with breakage ordestruction of the sensor, there will be a spill and probably spread ofthe fluid H over the food; as such said fluid H must be preferablynon-toxic, and it's nature may, as already mentioned, be similar to thatof the food, meaning that there will be no damage or contamination ofsaid food.

It is important to allow the consumer to easily see the current state ofpiston 5, whether it is at the position indicated by engraving 6 or not.When the sensor 1 is positioned as shown on FIGS. 3A, 3C and 3D it isquite easy, however the disposition illustrated on 3B does not afford aview of the side part of tube 2 of sensor 1, being visible only it's end3. Therefore, to acquire a view of whether the piston 5 has moved or notexclusively through the end 3, there is a constructive variant appliedto the sensor 1 comprising the addition of laminar, movable petals 7 onthe inside of tube 2, close to the face of piston 5 that faces the end3, as illustrated on FIG. 4A where said petals are seen in their closedposition, equivalent to the situation shown on FIG. 1B when the sensor 1has its fluid H perfectly frozen and the cap 17 has already beenexpelled, meaning also that the food is also frozen.

Once again, as already exposed on the lines above, if at any moment thetemperature reaches a value above the freezing point of fluid H, causingthawing, the fluid H will return total or partially to the liquid stateand will leak through the end 3 to the outside of tube 2, allowing themovement of piston 5, pushed by fluid O/spring M; said movement may beseen through the aperture of the petals 7 because the piston 5 haspushed them, as shown on FIG. 4B, indicating said temperature rise, withthe consequent thawing of the food. It is interesting that the petals 7and the piston 5 are presented in contrasting colors, in order to makeeasy the viewing; thus in the situation where the food is perfectlyfrozen what is seen through the end 3 are the petals 7 closed, withtheir characteristic color; when the food has thaw, what is seen throughthe end 3 is the face of piston 5, with it's characteristic color,contrasting to the color of the petals 7, which are at this particularmoment opened, hard to see.

Given it's simple constitution, the cost of the indicative sensor forstock control is very low, if compared to the price of the monitoredproduct. The monitored product presents a qualitative advantage uponcompeting with an equivalent product without such monitoring, because itincorporates the confidence that said product was correctly stored sinceits manufacture up to the moment it reaches the hands of the finalconsumer. The indicative sensor, being inside the package, has theadvantage of hindering adulterations or frauds. Furthermore, beingcompletely non-toxic, it is in intimate contact with the food, featuringa much more faithful monitoring, a much more real representation of thecritical history of time/temperature of the internal parts of the foodproduct, bringing about advantages compared to the state of the artsensors.

The sensor of the present invention features alternative options for thenature of the fluid H, in order to provide other temperatures for it'sfreezing/thawing point. If for the fluid H is used only pure water, thethawing point will be 0° C., which is the temperature of ice fusionunder the atmospheric pressure deemed normal. This way, if theindicative sensor for stock control is submitted to any temperatureabove 0’ C. it will register said happening, in the manner alreadyexplained. Adding to the fluid H jelly, salts and other compatiblesubstances, the temperature of the thawing point of fluid H changes tovalues above or below 0° C. As an example, in the case of addition ofjelly in any proportion to pure water, to form the fluid H, thefluidification point will be in a given temperature T above 0° C., andthe present sensor will therefore register the occurrence oftemperatures above said value T; if alcohol is added, in any proportion,the fluidification point will be in a temperature T′ below 0° C., andthe sensor will consequently register the occurrence of temperaturesabove the value T′.

Other kinds of materials may also be added to the fluid H, such as forexample a dye or pigment, to aid the viewing of said fluid; solidgranulate material may also be added, composed by tips/threads, to aidthe beginning of the fluid H nucleation, facilitating also the viewingof the sensor's indication; a tensoactive material, to facilitate themovement of the ice crystal of the sensor after the occurrence of apartial thawing, also insuring that there will be a good flowing of thefluid H already liquefied, totally defrost, and to facilitate thesolubilization of dyes/pigments along the fluid H.

Alternatively, a thermal insulation may also be provided between thesensor of the present invention and the monitored product; once there isa certain heat flow rate to cause the thawing of said fluid H, saidthermal insulation is set in the form of a vacuum layer; an air layer; awater layer; some other liquid layer or a layer of other insulatingmaterials placed between said sensor tube 2 and the food product to bemonitored. A manner to make it is to place the sensor 1 inside a plasticbubble hermetically closed that contains air or vacuum; this set formedby said plastic bubble with the sensor 1 inside is then placed along theproduct for monitoring.

Said tube 2 and piston 5 may receive diverse finishing according to theornamental aspect desired for the sensor 1, including total or partialpainting, and feature engraved details. FIG. 5 exhibits some variants ofpossible formats and finishing that may be used in the sensor of thepresent invention. In (a) is seen the piston 5 with it's lateralpresenting a horizontal stripe either painted or mounted; in (b), thepiston 5 with several horizontal stripes painted or mounted; in (c) atleast one of the faces of piston 5 presenting a color different fromthat of the lateral of the same piston; in (d) the piston 5 presentscharacters or signals written on the lateral and on at least one face ofthe same piston; the piston 5 presents one of it's faces with a convexshape, or alternatively, as illustrated on (e), concave shape; in (f)both the piston 5 and the tube 2 and the cap 17 feature a polygonalcross section, square in the case illustrated; in (g) the cap 17features a flexible wire or stem 8 connecting said cap 17 to the body 2,so that when the sensor 1 is placed in an ambient hat favors thefreezing of fluid H and this, frozen, expels the cap 17 to liberate theend 3, the cap 17 will not be free, lost in the middle of the foodproduct that is being monitored; on the contrary, the flexible stem 8keeps the cap 17 close and connected to the body 2, with the open end 3free for the flow of fluid H when this taws. In (h) is seen a stem 14connected to the face of piston 5 that sits facing the end 3, with thepurpose of causing yet more compression of the fluid 0 upon the assemblyof the sensor 1, with the fluid H in the liquid state, because uponplacing the cap 17 at the end 3, the cap pushes the stem 14 as well asthe piston 5 towards the end 4. In (i) the body 2 has its portioncorresponding to compartment C2 transparent, while the portioncorresponding to the compartment C1 is not transparent. In a great partof the body 2 is not transparent, however a region 19 of the same body 2is transparent, with region 19 constituting a viewing window that allowsthe viewing of piston 5 when the fluid H is defrost. In (k) the body 2features equally spaced markings, constituting a scale 20, in the regionclose to the position of piston 5; said scale 20 has the purpose ofallowing an estimative of the thawing time for the product monitored bythe sensor 1, for as said thawing occurs, as already explained, thepiston 5 moves inside the tube 2, along said scale 20.

FIG. 6 illustrates some other variants of constructive forms used on theindicative sensor for stock control at hand. In (l) is illustrated theexistence of a ring-shaped concavity 11 inside the tube 2, in lowerrelief, on the region of compartment C2, said concavity serving as ananchor for the fluid H, preventing the movement or sliding of said fluidH, while frozen, inside said compartment C2. Said anchoring ensured thatthe sensor will not present a mistaken indication due to the completesliding of the solid bloc of fluid H when frozen, allowing the piston 5to leave it's place. Said anchoring can also be effected, as shown in(m), by means of a shrivel 12 in higher relief in the internal wall ofcompartment C2. The shrivel 12 may be constituted by narrow bars,triangular teeth or other polygonal shapes; and said shrivel must belocated in an area relatively far from the area where the piston 5 isplaced, so as not to interfere on its movement. In (n) is seen a courselimiter 13 inside the tube 2, in higher relief, in the region ofcompartment C2, behaving in a similar manner to that of concavity 11with the same effect of anchoring, but now also being able to act as acourse limiter for the piston 5, when this moves due to the thawing offluid H. In (o) is seen a course limiter 18 inside the tube 2, in higherrelief, in the region of compartment C1, acting as a course limiter forthe piston 5 when this moves towards the end 4 to compress the fluid 0.In (p) is seen a preferential constructive form for the sensor 1, inwhich the end 4 features a concave shape, the releasable cap 17 convexshape, with the presence of said stem 14.

Continuing with FIG. 6, in (q) is observed that the open end 3 of tube 2was integrated to a collecting receptor 10, closed, which purpose is toreceive the fluid H when this taws. This prevents said fluid fromleaking to the food product that is being monitored, avoiding contactbetween them two; and the cap 17, upon being expelled from the end 3upon the freezing of fluid H, will also remain inside the collectingreceptor 10. Alternatively, receptor 10 may feature an open end wheneverthe mixing between the food product and the fluid causes no harm. In (r)is shown said collecting receptor 10 with it's internal wall coveredwith a absorbent material 15, which function is to absorb the fluid Hwhen this is liquefied. The material 15 can be constituted by a chemicalpowder or by a paper or absorbent foam sheet; said material 15 may reactchemically with the liquefied fluid H, upon absorbing it, so that itpresents a contrasting color to aid the viewing of the indication of thesensor of the present invention when taw occurs. In this scope, it ispossible, alternatively, that the collecting receptor 10 has acharacteristic physical disposition, in the shape of drawings orsymbols, in such a way that the presence there of the fluid H, defrost,brings up a contrasting color of this same drawings or symbols. In (s)is seen a membrane 16 closing the end 3 exactly at the integration pointbetween said end and the collecting receptor 10; this membrane 16 isthin, and can be made of plastic, paper or equivalent material of adelicate constitution, replacing the cap 17, in such a way hat when theindicative sensor for storage control suffers the freezing process,deriving from the first and only time in which said sensor will be used,the frozen fluid H expands and part of, or all of the membrane 16 isruptured; when the fluid H is liquefied, on the thawing of the monitoredproduct, it flows to the collector 10 passing by the end 3 and theruptured membrane 16. Alternatively, closing the end 3, the membrane 16may exist even if there is no collecting receptor 10 integrated to theend 3.

FIG. 7 shows more variants of constructive forms used on the indicativesensor for storage control of the present invention. In (t) the cap 17has a hinge 22 connecting said cap 17 to the body 2, acting in the sameway that the flexible stem 8, already explained: when the fluid H of thesensor 1 freezes, there is the expulsion of the cap 17 but this does notcome free, because the hinge 22 keeps the cap 17 close and connected tothe body 2, with the open end 3 free for the flow of fluid H when thistaws. In (u) the end 3 of body 2 features fasteners 21 that keep the cap17 close to the body 2, when the fluid H freezes and the cap 17 isexpelled; however, the fasteners 21 have a shape and physical dimensionssuch that they allow that the end 3 remains free and open to the flow offluid H, when this taws, regardless of the proximity of cap 17previously dropped. In (v), in an enlarged view, the piston 5 presents atridimensional object or physical shape 23 applied to at least one faceof the same piston. In (w) the laminar petals 7 are located near the end3, inside the collecting receptor 10, or even said petals coincide withthe very end 3, with a spacing 24 between said petals 7 and the cap 17.

FIG. 9 illustrates yet another variant of the indicative sensor forstorage control, in which there simply is no compartment C1, featuringonly compartment C2. The sliding piston 5 is positioned close to the end4, and there is also optionally the passing hole 25 which allows theentrance of air in the tube 2 upon the movement of the sliding piston 5.A spring M′, relaxed, is placed in the compartment C2, with one of itsends attached to the sliding piston 5 and its other end attached to cap17; the compartment C2 is, as already described, filled with the frozenfluid H. the operation of this variant of the indicative sensor forstorage control is also identical to the one already explained, with thefluid H freezing and ejecting cap 17 from the end 3; when fluid H thaws,the spring M′, which is relaxed, pulls the sliding piston 5 towards theend 3 of tube 2, aiding in the ejection of fluid H from compartment C2.

The stock control sensor, before being subject to its first and onlyfreezing, may be placed along a heated product or an already hotproduct; when said product, along with the sensor, is placed in anambient that favors freezing, the fluid (H) also freezes, with thebeginning of the storage monitoring of the product.

The present indicative sensor for storage control is not limited to useon food, and can be used along with any product which freezing onewishes to monitor, for example, blood bags, medicine, resins used inmanufacturing processes, etc.

With a description of a preferential incorporation example, it must beunderstood hat the scope of the present invention covers other possiblevariants, being limited only by the contents of the appended claims,there including the possible equivalents.

1. “INDICATIVE SENSOR FOR STOCK CONTROL”, characterized by the fact ofcomprising a sensor (1) featuring: a hollow tube (2) with a first openend (3) and a second closed end (4); a slidable piston (5) inside thetube (2); a fluid (O) or a spring (M) contained in a compartment (C1),inside the tube (2), comprised between the piston (5) and the end (4); afluid (H) contained in a compartment (C2), inside the tube (2),comprised between the piston (5) and the end (3); media to provide atleast one indication of the occurrence of a temperature rise in theambient in which the sensor (1) is immersed. 2.-40. (canceled)
 41. Asensor for stock control, comprising: a hollow tube having an open endand a closed end; a piston positioned inside the hollow tube, whereinthe piston creates a first space between a first side of the piston andthe open end and a second space between a second side of the piston andthe closed end, the piston having a circumference in contact with thehollow tube; a first fluid in the first space; a force generating objectin the second space; and media associated with the hollow tube toprovide at least one indication of the occurrence of a temperature risein an ambient in which the sensor is immersed.
 42. The sensor of claim41, wherein the piston is irreversibly movable within the hollow tube.43. The sensor of claim 41, wherein the first fluid in the first spaceis frozen in a solid state.
 44. The sensor of claim 43, furthercomprising a releasable cap positioned in the open end of the hollowtube wherein the releasable cap maintains the first fluid in the firstspace and wherein the releasable cap may be released upon expansion ofthe first fluid due to freezing.
 45. The sensor of claim 41, wherein theforce generating object comprises a gaseous fluid.
 46. The sensor ofclaim 41, wherein the force generating object exerts a force on thesecond side of the piston thereby tending to push the piston towards theopen end of the hollow tube.
 47. The sensor of claim 41, wherein theforce generating object comprises a spring.
 48. The sensor of claim 41,wherein the first fluid prevents movement of the piston when the firstfluid is frozen.
 49. The sensor of claim 41, wherein the first fluid isinitially in a frozen state and wherein exposure of the sensor to anambient temperature above a melting point of the first fluid liquefiesat least a portion of the frozen first fluid allowing movement of thepiston.
 50. The sensor of claim 41, wherein the first fluid comprises anon-toxic fluid.
 51. The sensor of claim 41, wherein the hollow tubecomprises a hollow tube constructed of a rigid material.
 52. The sensorof claim 41, wherein the media associated with the hollow tube toprovide at least one indication of the occurrence of a temperature risein an ambient in which the sensor is immersed comprises an engraving onthe hollow tube coinciding with the position of the piston within thetube when the first fluid is frozen.
 53. The sensor of claim 41, furthercomprising movable laminar petals positioned within the hollow tubebetween the first space and the second space.
 54. The sensor of claim53, wherein the movable laminar petals exhibit a closed position whenthe first fluid is in a frozen state within the first space.
 55. Thesensor of claim 53, wherein the movable laminar petals exhibit an openposition when the first fluid is in a non-frozen or partially thawedstate.
 56. The sensor of claim 53, wherein the movable laminar petalsand the piston feature colors that are contrast each other.
 57. Thesensor of claim 41, further comprising at least one additive mixed withthe first fluid, wherein the at least one additive is selected from thegroup consisting of jelly, salts, fluid freezing modifiers, and fluidthawing modifiers.
 58. The sensor of claim 41, further comprising agranulated solid material mixed with the first fluid, wherein thegranulated solid material promotes nucleation of the first fluid. 59.The sensor of claim 41, further comprising a tensoactive material mixedwith the first fluid, wherein the tensoactive material facilitates themovement of ice crystals in the first fluid when in a partially frozenstate.
 60. The sensor of claim 41, further comprising thermal insulationsurrounding at least a portion of the sensor.
 61. The sensor of claim41, further comprising: a releasable cap positioned in the open end ofthe hollow tube wherein the releasable cap maintains the first fluid inthe first space and wherein the releasable cap may be released uponexpansion of the first fluid due to freezing; and a communication deviceconnected to the releasable cap and the hollow tube, wherein thecommunication device maintains connection between the releasable cap andthe hollow tube when the releasable cap is detached from the open end ofthe hollow tube.
 62. The sensor of claim 41, further comprising acollecting receptor for collecting any first fluid expelled from thefirst space in the hollow tube.
 63. The sensor of claim 62, wherein thecollecting receptor further comprises an absorbent material forabsorbing any first fluid collected by the collecting receptor.
 64. Thesensor of claim 63, wherein the absorbent material comprises anabsorbent material capable of reacting with the first fluid to promote acolor change of the absorbent material.
 65. The sensor of claim 41,further comprising a breakable thin membrane attached to the open end ofthe hollow tube, wherein the thin membrane contains the first fluid inthe first space of the hollow tube.
 66. The sensor of claim 41, furthercomprising a feature for preventing movement of the first fluid in afrozen state within the first space, the feature selected from the groupconsisting of a ring-shaped concavity and a shrivel.
 67. The sensor ofclaim 41, further comprising a course limiter inside the hollow tube tolimit the movement of the piston within the hollow tube.
 68. The sensorof claim 41, further comprising an additive mixed with the first fluid,the additive selected from the group consisting of dyes, pigments, andcoloring.
 69. The sensor of claim 41, wherein the piston furthercomprises at least one horizontal stripe on the circumference of thepiston in contact with the hollow tube.
 70. The sensor of claim 41,wherein the piston further comprises a piston with at least the firstside or the second side having a shape selected from the groupconsisting of a concave shape and a convex shape.
 71. A sensor,comprising: a hollow form having an open end and a closed end; amoveable piston positioned in the closed end of the hollow form; a cappositioned in the open end of the hollow form; a relaxed spring attachedto the moveable piston and the cap; and a fluid in the hollow formbetween the moveable piston and the cap, the fluid capable of beingfrozen.
 72. The sensor of claim 71, wherein the hollow form comprises ahollow form having a shape selected from the group consisting of across-sectional circular tube, a cross-sectional square tube, and across-sectional polygonal tube.
 73. The sensor of claim 71, furthercomprising a hole in the closed end of the hollow form, the holeallowing air to flow into the hollow form as the moveable piston moveswithin the hollow form.
 74. The sensor of claim 71, further comprisingspaced markings on the hollow form, the spaced markings in a positionrelative to the moveable piston.
 75. A method for monitoring frozengoods, comprising: placing a sensor within the vicinity of a frozen goodto be monitored, the sensor comprising: a hollow form having an open endand a closed end; a piston positioned inside the hollow form, whereinthe piston creates a first space between a first side of the piston andthe open end and a second space between a second side of the piston andthe closed end, the piston having a surface in contact with the hollowform; a first fluid in the first space, wherein the first fluid is in afrozen state; and a force generating object in the second space.
 76. Themethod of claim 75, wherein the first fluid has a melting point similarto a melting point of a fluid in the frozen good.
 77. The method ofclaim 75, wherein placing the sensor within the vicinity of a frozengood comprises placing at least one sensor at a location relative to thefrozen good, wherein the location is selected from the group consistingof placing at least one sensor on the outside of the frozen good,placing the at least one sensor in the frozen good, and placing the atleast one sensor in a blister pack with the frozen good.
 78. The methodof claim 75, wherein the sensor further comprises a thermal insulationsurrounding at least a portion of the sensor.
 79. The method of claim75, wherein the frozen good comprises at least one frozen good selectedfrom the group consisting of food, blood bags, medicine, resins, andpharmaceuticals.